Device and Associated Percutaneous Minimally Invasive Method for Creating a Venous Valve

ABSTRACT

A device includes a stent scaffold structure supporting a patch on an interior surface thereof. The device may be used to produce a neovalve in a percutaneous minimally invasive manner. Exemplary methods include implanting the device, permitting a growth layer to form over at least a portion of the patch, and separating the patch from the stent scaffold thereby forming a slit or gap in the vessel wall to act as a valve similar to the surgical neovalve.

BACKGROUND

Chronic venous insufficiency (CVI) is a long-term condition caused bymalfunctioning (incompetent) valves in the veins. It may also occur asthe result of a past blood clot in the legs. CVI is a medical conditionwhere the valves of the vein do not fully close and permit blood totravel upstream. The condition causes blood to pool in the legs. FIGS.1A-1B illustrate an exemplary vein having a properly functioning valvein which blood may pass through the vein in a single direction back tothe heart. FIGS. 1C-1D illustrate an exemplary vein suffering fromchronic venous insufficiency in which the vein valve does not fullyclose and thereby permits blood to flow away from the heart. Typicalsymptoms include swelling of the legs, varicose veins and ulcers.

Currently, the only effective way to replace a damaged valve is surgeryto either modify an existing valve or create a new valve by separatingvenous wall layers. However, these methods are extremely invasive andrequire the external access to the vein through dissection. FIGS. 2A-2Cillustrate an exemplary deep venous reconstruction surgery in which thevein is opened in FIG. 2A, the venous layers are dissected in FIG. 2B,and a valve is created from the dissected layers in FIG. 2C. Asillustrated, the surgery is very invasive requiring external veindissection, reconstruction, and closure.

SUMMARY

Exemplary embodiments include a device that can be used to produce aneovalve. Exemplary embodiments include a stent, stent-like scaffold, orother support structure (generally referred to as stent herein) toposition or retain a patch along a portion of a vessel wall. Theexemplary embodiment may also include a patch removably attached to thestent. The patch may be on a luminal surface of the stent and maytraverse only a portion of the interior circumference of the stent, suchthat the patch does not fully encircle the lumen of the stent. A portionof the patch may be coated or otherwise have a layer, surface structure,or other feature to inhibit or enhance endothelial, smooth muscle cell,or other tissue layer (hereinafter referred to as growth layer)proliferation.

Exemplary embodiments include a method to produce a neovalve in apercutaneous minimally invasive manner using exemplary embodiments ofthe device described herein. In an exemplary embodiment, a devicecomprising a stent and a patch removably attached to an interior surfaceof a stent is provided. The device may be delivered percutaneously andminimally-invasively to a desired location to form a replacement veinvalve. The device may be delivered, deployed, and left in place at thetarget vein for sufficient time to form a growth layer on at least aportion of the patch. For example, the device may be implanted forapproximately 4-8 weeks or other period of time determined to besuitable. After the patch is covered by the growth layer, such ascompletely covered, or substantially covered, the patch is separatedfrom the stent and removed from the body. In an exemplary embodiment,the patch is substantially covered while a retrieval device remainsuncovered and positioned near a center of the vessel. In this case, thepatch is separated and removed by engaging the retrieval device andimposing an external force on the patch, thereby separating it from thestent. In an exemplary embodiment, the retrieval device is engaged by asnare. In an exemplary embodiment, the retrieval device comprises anextension that reaches to an exterior position outside of the body, whenthe patch is positioned within the body and covered by the growth layer.An external force is applied to the extension, which translates throughthe body to the patch, and thereby separating the patch from the stent.

Exemplary embodiments include creating a slit or flap at a vessel wallby separating the growth layer from a vessel wall lumen and/or from astent. In order to aid in the removal of the patch, and/or in thecreation of the slit in the vessel wall, the method may includeinhibiting the proliferation of cells at a portion of the patch.Therefore, the patch may be coated or otherwise have a layer, surfacestructure, or other feature to inhibit cell proliferation. An exemplaryembodiment may therefore include exposing a leading edge of the patch byinhibiting an vascular tissue layer from forming thereover during theimplanted duration. Exemplary embodiments use the space left behindafter the patch is removed from within the vessel wall to cause thevessel wall layers to be separated due to the blood flow. Exemplaryembodiments therefore may permit the luminal side of a vessel wall toact as a valve similar to the surgical neovalve.

DRAWINGS

FIGS. 1A-1D illustrate and exemplary human vein in cross section havinga valve either properly function in an open and closed configuration orimproperly functioning in an open and incompletely closed configuration.

FIGS. 2A-2C illustrate photographs taken from an invasive conventionalsurgical procedure to replace a damaged valve. See Maleti, O., DeepVenous Reconstructive Surgery for C.V.I. New Procedures and Tricks.Controversies and Updates in Vascular Surgery, January 2014.

FIGS. 3-7 illustrate exemplary representative stents and stentscaffolding structures the may be used in exemplary embodiments.

FIG. 8A-8C illustrate exemplary devices for creating a neovalveaccording to embodiments.

FIG. 9 illustrates an exemplary patch used in conjunction withembodiments described herein.

FIG. 10 represents an exemplary flow diagram to perform a method ofcreating a neovalve using embodiments described herein.

FIGS. 11A-11B illustrate the device as implanted in the body accordingto exemplary embodiments described herein.

DESCRIPTION

The following detailed description illustrates by way of example, not byway of limitation, the principles of the invention. This descriptionwill clearly enable one skilled in the art to make and use theinvention, and describes several embodiments, adaptations, variations,alternatives and uses of the invention, including what is presentlybelieved to be the best mode of carrying out the invention. It should beunderstood that the drawings are diagrammatic and schematicrepresentations of exemplary embodiments of the invention, and are notlimiting of the present invention nor are they necessarily drawn toscale.

Exemplary embodiments described herein include a device to produce aneovalve through a percutaneous minimally-invasive method. Exemplaryembodiments include a stent or stent-like scaffold and patch removeablyattached to the scaffold. The device may include a retrieval componentto remove the patch from the scaffold. Methods of creating the neovalvemay include delivering the device to the target vein and leaving thedevice in place according to known stenting methods. After a sufficientperiod of time, such that the device is covered by a growth layer, thepatch may be removed which creates a slit in the vessel wall. The spaceleft behind the patch within the vessel wall may be used to cause thevessel wall layers to separate and permit the luminal side of the wallto act as a valve similar to the surgical neovalve.

Although embodiments of the invention may be described and illustratedherein in terms of a stent support structure, it should be understoodthat embodiments of this invention are not so limited, but areadditionally applicable to other support structures in which a patch isheld against a luminal vessel wall. Furthermore, although embodiments ofthe invention may be described and illustrated herein in terms ofexemplary retrieval components, it should be understood that embodimentsof the invention can use any combination of retrieval method ormechanism.

Stent constructions generally include cylindrical frames that areexpandable from a collapsed, reduced diameter delivery configuration toa deployed, larger diameter configuration for support and/or contact ofthe luminal vessel wall. In an exemplary embodiment, the stent framedefines a plurality of openings that facilitate tissue ingrowth.

There are two broad classes of stents: self-expanding stents and balloonexpandable stents. Self-expanding stents are typically characterized byintraluminal expansion when a constraining force is removed, such as anouter sheath of a stent delivery system, and/or in the presence of anelevated temperature (due to material properties of the stent).Self-expanding stents are generally loaded into a stent delivery systemby collapsing the stent from an expanded configuration at a first largerdiameter to a collapsed configuration at a second smaller diameter.Balloon expandable stents are typically characterized by intraluminalexpansion via an inflation force, such as a balloon catheter. Balloonexpandable stents are generally loaded onto a balloon catheter through acrimping process to transition the stent to a collapsed configuration,and are plastically deformed when the balloon is inflated in the bodyvessel to the expanded configuration.

There are two basic architectures for stents, circumferential andhelical. Circumferential configurations generally include a series ofcylindrical rings, formed by a series of connected struts, joinedtogether by connecting elements or bridges along a longitudinal axis ofthe stent. Helical configurations include a continuous helical structurealong the longitudinal axis of the stent with adjacent windings, formedby a series of connected struts, connected by one or more connectingelements or bridges.

Any scaffold structure may be used to support the patch describedherein. For example stents described in U.S. Pat. Nos. 6,488,703;6,579,314; 8,518,101; 9,066,825; 9,265,636; and U.S. Publication Nos.2015/0039078 may be used. The disclosure of each is hereby incorporatedby reference in its entirety herein.

The patterns shown and described herein may be incorporated into anyintraluminal prosthesis, such as a self-expanding stent or a balloonexpandable stent, and helical or circumferential configurations, withoutlimitation. In one embodiment, the patterns disclosed herein may bemachined (e.g., laser machined) into a seamless tube of metal orpolymer. Non-limiting examples of potential metal tubes includestainless steel (e.g., AISI 316 SS), titanium, cobalt-chromium alloys,and nickel titanium (Nitinol). In other embodiments, the patternsdisclosed herein may be formed into a sheet of metal or polymer that isrolled into a tubular shape. The tubes or sheets may be heat-treatedprior to machining the pattern therein, and the machined tubes or sheetsmay be annealed and/or electro-polished. Other known pre-processing andpost-processing methods are also contemplated herein. The pattern ofstruts and connecting elements can be configured depending on thedesired attributes. For example, the pattern can be configured toenhance flexibility or bendability. The pattern can also be configuredto ensure uniform expansion and prevent foreshortening of the stent uponintraluminal expansion. The pattern can also be configured to facilitatetissue growth over the structure and attached patch.

FIG. 3 illustrates an exemplary stent structure comprising a helicalstent construction. In an exemplary embodiment, the stent 30 has atubular shape and a first end, a second end, an intermediate portion,and a longitudinal axis. The intermediate portion includes a continuoushelical winding 32. The winding 32 has a plurality of circumferentialsections that join together end-to-end and circumscribe the axis fromthe first end to the second end, with the continuation of eachcircumferential section along the path of the helical windingrepresented with dashed lines in FIG. 3. The portions of the stent inthe background of the figure are not shown in detail, for clarity and toclearly show identical features already presented in the foreground ofthe figure. Although only one helical winding is illustrated in FIG. 3,more than one helical winding can be employed in the stent. For example,a helical winding with a first helical angle can be connected or coupledwith another helical winding that has a different second helical angle.Alternatively, the helical winding can be used as a central portion ofthe intermediate portion and a different helical winding can be usedproximate each end of the intermediate portion. As shown, the stent mayinclude at least one bridge 34 configured to connect one circumferentialsection to an axially-spaced adjacent circumferential section. Thebridge may extend generally circumferentially around the axis 16 on agenerally orthogonal plane with respect to the axis, or may extendgenerally parallel with the axis or along any angle in between.Preferably, a plurality of bridges 34 interconnect circumferentialsections to adjacent circumferential sections.

FIGS. 4-5 illustrate exemplary circumferential stent configurations. Asshown, the stent 40 defines a single unitary piece that conceptuallycomprises a plurality of rings stents 42 joined by bridges 44. The ringstents 42 may comprise a plurality of zig-zag struts 43 of the same ordifferent lengths. FIG. 4 illustrates an exemplary stent constructionhaving struts of approximately the same length, while FIG. 5 illustratesan exemplary stent construction having struts of different lengths tooffset facing apex of joined struts from adjacent stent rings. Thebridges, similar to the disclosed helical configuration may be parallel,orthogonal, or any angular orientation in between with respect to thestent axis.

FIG. 6 illustrates an exemplary stent configuration integrating conceptsof the helical and circumferential structures into a singleconstruction. As shown, the stent 60 comprises a stent body that can behollow and generally cylindrical. The stent body can include a pluralityof struts 63. Further, the struts can establish a plurality of cellswithin the stent body. The struts can be in the form of aninterconnected network or matrix that is generally continuous. Thestruts can form a repeating pattern that can define an array of cells.The cells, as shown, can be closed. However, it is noted that the stentmay have localized areas in which other struts do not form closed cells.In other words, the stent can be a closed-cell stent in which each cellis separate from adjacent cells. Alternatively, the stent can be anopen-cell stent in which one or more struts between two or more adjacentcells is removed from the construction of the stent. In a particularembodiment, as shown, each cell can be hexagonally shaped.Alternatively, each cell can be generally diamond shaped, generallyelliptical, or another shape that can allow the stent to be collapsed asdescribed herein. A string or plurality of cells can be alignedhelically or arranged circumferentially around the stent body.

FIGS. 3-6 illustrate stent constructions comprising generally straightstruts when in a contracted or delivery configuration. However, stentstruts can have any configuration. For example, as shown in FIG. 7, thestrut pattern may be generally curved or a combination of straight andcurved. Referring to FIG. 7, a stent 70 is shown, including asequentially repeating pattern of stent cells aligned along a series ofcircumferential axes perpendicular to a longitudinal axis. Any number ofcircumferential axes along which the pattern of stent cells is arrangedis possible, depending on various stent dimensional features including,for example, overall stent length, stent cell length, connector length,etc. The stent cells are formed by stent struts 73 described hereinaccording to how these cells resemble various letters, the stentelements repeating along the circumferential axes. Beginning from thetop left side of FIG. 7, a repeating series of stent struts is shownalong a first side of the stent cells, the stent elements including Rshapes and U shapes, i.e., R-shaped stent elements and U-shaped stentelements. According to one embodiment, the R-shaped stent elements aresimilar or identical to those described in U.S. Pat. No. 6,821,292,which is incorporated by reference in its entirety into thisapplication.

The stent structures provided herein are exemplary only. Any frameworkthat supports a patch against a vessel wall and permits the growth of anew tissue layer thereover is within the scope of the instantdisclosure. Although an open stent structure is generally shown anddescribed, in which one or more openings are positioned in the stentwall, other configurations may also be used. The openings may be ofdifferent sizes, such as those present in a woven configuration or in amesh, fiber, or other stent or graft structure. Any such configurationis included in the term support scaffold. In an exemplary embodiment,the support scaffold is configured to approximately the interior vesselprofile. For example, the support scaffold may be generally cylindricalor tubular in shape. The support scaffold may include apertures throughthe scaffold wall. The support scaffold may include connected strutsthat are expandable from a contracted configuration having a reduceddiameter profile to an expanded configuration having an increaseddiameter profile larger than the reduced diameter profile. The supportscaffold may also be made of different materials. For example, the stentmay comprise stainless steel (e.g., AISI 316 SS), titanium,cobalt-chromium alloys, nickel titanium (Nitinol), Cobalt-Nickel alloy,metal, metal alloy, and combinations thereof. The stent may also be madeof a bioresorbable materials, such as, for example, magnesium, zink,poly(L-lactide).

FIGS. 8A-8C illustrate an exemplary embodiment of a device 80 to producea neovalve through a percutaneous minimally-invasive method. FIG. 8Aillustrates a perspective view of the exemplary device while FIG. 8Billustrates a first side profile view and FIG. 8C illustrates a secondside profile view orthogonal to the FIG. 8B side view. Exemplaryembodiments include a stent or stent-like scaffold 86 and a patch 88removeably attached to the scaffold. The device may include a retrievalcomponent to remove the patch from the scaffold. The stent may compriseany pattern shown and described herein or known in the art, such as aself-expanding stent or a balloon expandable stent, and helical orcircumferential configurations, without limitation. Exemplary stentconfigurations are provided above for illustration only and are notintended to limit the disclosure. A generic tubular structure isillustrated to represent the stent or stent-like scaffold withoutidentifying any particular form to illustrate the interchangeability ofthe stent structures.

The device 80 includes a removeably attached patch 88 on a luminalsurface of the stent 86. As shown, the patch covers only a portion ofthe luminal surface of the stent 80. The covered portion may not fullycircumscribe the stent, such that the patch may not form a complete ringor closed loop. The patch may include a first and second terminal end.The first terminal end may be positioned at, adjacent, or proximate aterminal end of the stent. The first terminal end may define an arclength L1 around a portion of the interior circumference of the luminalsurface of the stent. The arc defined by the first terminal end maycircumscribe approximately half of the stent perimeter. For example, thepatch may extend around 30-60 percent of the interior circumference ofthe stent. When seen in profile, the patch may extend symmetrically downtoward the middle of the stent profile. For example, the patch mayextend from a top edge to approximately 45-60 percent, or 48-55 percent,and approximately 50 percent across the stent diameter when seen inprofile. The patch longitudinal length may also be approximately equalto or just less than the longitudinal length of the stent. In anexemplary embodiment, the patch length is 80 to 100 percent of the stentlength, or 90-98 percent of the stent length.

In an exemplary embodiment, the patch tapers from the first end to thesecond end, such that the arc length of the first end L1 is greater thanan arc length of the second end L2, where the arc length is measuredperpendicular to the device axis. The patch may define other shapes. Inan exemplary embodiment, the patch does not taper but maintains aconstant arc length along its length thereby defining a rectangularpatch when see in profile. The exemplary illustrated patch isillustrated in a dashed line to indicate its position on the interiorsurface of the stent structure.

In an exemplary embodiment, the patch 88 comprises a flexible orsemi-flexible material that conforms to the luminal surface of the stent86. The material is flexible or semi-flexible to permit movement of thedevice during navigation through tortious vessels to a delivery sitewithin the vasculature of a patient. The material is flexible in that itmay be deformed. The material may be semi-flexible in that it can retainits shape when unsupported by the scaffold structure, but flexible tocontort under application of an outside force to navigate the tortuouslumens to the deployment site. In an exemplary embodiment, the patch isnon-rigid in that is have sufficiently flexibility to crimp to the stentstructure and define a reduced profile delivery configuration and anexpanded profile deployed configuration.

The patch 88 may be made in various configurations and materials. Forexample, a thin metal sheet may be used. In an exemplary embodiment, thepatch and the stent are made of the same material, such as Nitinol,steel, titanium, Cobalt-Nickel alloy, or metal or metal alloy. The patchmay also or alternatively comprise a fine wire mesh. To reduce tissueingrowth through the patch, the patch may be coated with anothermaterial. For example, a urethane may be used to coat the mesh andprevent tissue penetration through the mesh apertures. The patch mayalso include non-metal combinations. For example, the patch may includean expanded polytetrafluoroethylene (ePTFE).

The patch 88 may be coated with drugs to inhibit cell proliferationalong a portion of the patch. In an exemplary embodiment, the patch 88may be coated on an interior or luminal surface along a portion atand/or adjacent the terminal end of the patch. In this exemplaryembodiment, the leading edge of the patch is not covered with a growthlayer after implantation of the device because of the presence of thedrug coating. Therefore, the patch may be more easily removed to createthe neovalve. An exemplary coated region 89 is illustrated by across-hatch pattern in FIGS. 8B and 8C. The patch 88 may also be coatedwith a drug or include a surface texture to encourage cellularproliferation across a majority of the patch.

In an exemplary embodiment, the patch is removably coupled to the stent.The patch may be coupled to the stent in any fashion. For example,methods employed to couple grafts to stent surfaces may be used. Thepatch may be removably coupled to the stent by manipulating the bondingstrength between the stent and the patch. For example, the patch may beadhered to the stent with sufficient strength to retain the patch inplace despite the shear stress imposed by the blood passage. However,the adhesive strength may be overcome by the addition of an externallyapplied force, such as that imposed through a retrieval device,described in more detail herein. The attachment strength may alsodegrade over time, such as by use of resorbable or degradable agents.Therefore, when initially implanted, the patch may be more securelycoupled to the stent when the experienced sheer stress is greatest. Asthe growth layer forms over the graft, the attachment strength betweenthe stent and patch may be reduced as the growth layer may be used toprovide the requisite support for the patch to retain it in place untilit is removed.

In the case of a metallic patch or a patch including a metal component,the patch may be welded to the stent. The patch may be sufficiently thinto permit its removal by tearing or otherwise separating from the weldlocations. In an exemplary embodiment, the patch is perforated oraltered, such as by having a reduced thickness, to facilitate separationof the patch from the stent when an external force is applied. If thepatch include a wire mesh, the mesh wire may be used to attach the patchto the stent.

In one embodiment, the stent 86 may include a coating. The coating maycover substantially the entire surface area of the stent structurecorresponding to the patch area or may only cover a portion thereof. Thecoating may include a polymer that is capable of adhering to the patch88, through the application of, for example, heat, pressure, solvents,adhesives (e.g., bio-resorbable adhesives), or combinations thereof.Suitable polymers for the coating may include, for example,polytetrafluoroethylene (PTFE), ePTFE, polyurethane, fluorinatedethylene propylene (FEP), an amorphous fluoropolymer, and combinationsthereof. In a preferred embodiment, the polymer includes an amorphousfluoropolymer including tetrafluoroethylene (TEF) and4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole, or aperfluoroelastomer, as described in U.S. Patent Application PublicationNo. 2005/0131527, which is incorporated by reference in its entiretyinto this application. The coating may be in the form of particles orpowder, and may be applied to the stent 86 and/or to the patch 88 byspraying, dip coating, or other methods known to one skilled in the art.In one embodiment, the coating is a fluoropolymer including TEF inpowdered form which is disposed directly on a surface of the patch 88 sothat when the stent 86 is positioned on the surface, the powder ispositioned between the patch and a surface of the stent.

Attachment of the stent to the patch may be accomplished by variousmethods, which can be facilitated by the materials chosen for the stent,patch and/or coatings, if used. For example, if an ePTFE patch is used,it may be positioned over a mandrel. The ePTFE patch may be sintered,unsintered, or partially sintered. A stent with a polyurethane coatingmay be positioned along the outer (abluminal) surface of the ePTFEpatch. In one embodiment, the stent may be pre-dilated (expanded) by atool for moving into position on an outer surface of the patch.Depending on the material properties of the stent, an additionalcrimping step may be required to secure the stent in position. Once thestent is initially positioned on a surface of the patch, the mandrel maythen be removed from the assembly and the inside surface of the ePTFEpatch may be sprayed, with a solvent, such as tetrahydrofuran (THF), sothat the THF migrates through the wall of the patch. The spraying may beaccomplished using different methods known to one skilled in the art.For example, the patch may be suspended such that a surface of the graftis accessible; a spraying mechanism may be inserted into the stent lumenand rotated to contact THF with a surface of the patch. Alternatively, amandrel with openings may be inserted into the lumen, the mandrelattached to a source of THF, where the THF is delivered to the mandreland through the openings to contact a surface of the patch. Anotherpossibility includes using a needle device attached to a source of THFand inserting the needle through the wall of the stent at variouslocations, where THF is delivered through the needle at each location tocontact a surface of the patch. The interaction between the ePTFE, THFand polyurethane coating on the stent bonds the annular members to theePTFE graft (the THF or other aprotic solvent is believed to dissolvepolyurethane, such that when a small amount contacts the polyurethanecoating, a mechanical bond is developed between the coating and theePTFE patch).

In another embodiment, a suitable solvent, such as, for example, anaprotic solvent including dimethylacetamide (DMAC), dimethylforamide,THF, or their mixtures, is sprayed or otherwise disposed over theoutside surface of the patch after the stent has been positionedthereover. Alternatively, the ePTFE patch with the stent could be dipcoated in a suitable solvent. In yet another embodiment, the stent iscoated with PTFE and the ePTFE patch is initially unsintered. Followingplacement of the stent over the patch, the assembly is heated above thecrystalline melt point of PTFE to sinter the stent to the patch.

It is within the scope of the present disclosure to provide a graftlayer to facilitate attachment of the patch to the stent. For example,an annular graft member could be disposed on an outer surface of thestent and the patch attached to the stent and/or the graft memberthrough openings in the stent wall. Therefore, the stent could bedisposed between a generally tubular graft layer and strips of coveringmaterial defining a patch. The graft and/or patch may be perforated orotherwise altered at or proximate the attachment points to facilitateremoval of the patch.

In one attachment method, stent 86, which may or may not include acoating, is woven into a portion of the patch. In one embodiment,annular members of a stent having a zig-zag configuration of struts arewoven into the patch. In an exemplary embodiment, sutures may be used toattach the stent to the patch. The sutures may be resorbable,non-resorbable, or a combination of a set of sutures that are resorbableand a set of sutures that are not resorbable. In certain embodiments,additional or alternative attachment methods are used such as bonding,welding, weaving, sutures, spraying with a solvent, such as THF (e.g.,the stent including a coating, such as polyurethane), disposing anadhesive, such as a bio-resorbable and/or non-bio-resorbable adhesive,over one or more surfaces of the patch (e.g., at locations of contactwith the stent), heating the stent-patch (e.g., the ePTFE is unsinteredand the stent includes a coating, such as PTFE), applying a uniformpressure to the assembled stent-patch along both inner and outersurfaces, or any combination thereof.

In an exemplary embodiment, the stent, the patch, the attachmentmechanism between the patch and the stent, and any combination thereofmay be resorbable such that the neovalve is created without the removalof the patch. In an exemplary embodiment, the attachment between thestent and the patch is resorbable such that after the growth of thegrowth layer, the patch and the growth layer together separate as asingle layer from the stent and the vessel wall. In an exemplaryembodiment, the patch is resorbable such that when the patch degrades,the growth layer separates from the stent and vessel wall. Theattachment mechanism, such as the suture, adhesive, etc. and/or thepatch may be resorbable by the application of a solvent or may bebioresorbable such that it degrades in the presence of blood or bodilyfluid.

In an exemplary embodiment, the device may include multiple patchessupported by a single stent. For example, two or more patches may be onopposing lateral sides of the stent such that once implanted andremoved, the separated growth layers may form a valve similar to aduckbill valve. In an exemplary embodiment, two or more patches arecircumferentially offset around a circumference of the stent and may becoextensive along a longitudinal length of the stent, such that thepatches overlap when viewed in profile. The device may also includemultiple patches longitudinally separated along a longitudinal length ofthe stent, such that a series of sequential valves would be createdalong a vein length. In this case, when seen in profile, the patch mayextend symmetrically down toward the middle of the stent profile. Forexample, the patch may extend from a top edge to approximately 25-75percent, or approximately 25-50 percent across the stent diameter whenseen in profile and/or a second patch may extend from a bottom edge toapproximately 25-75 percent, approximately 25-50 percent, orapproximately 25 percent across the stent diameter when seen in profile.In an exemplary embodiment, three or four patches are usedcircumferentially offset around an interior perimeter of the stent.

In an exemplary embodiment, the patch may also include a retrievaldevice. FIG. 9 illustrates an exemplary patch 98 comprising a retrievaldevice 99. The retrieval device may be any extension or feature that canbe captured, snared, attached, grasped, or otherwise manipulated toprovide a surface or structure to remove the patch after the growthlayer has formed. As shown, the retrieval device provides a loop or hookthat may be used in conjunction with a snare to permit an external forceto pull and remove the patch from between the vessel wall/stentstructure and the grown growth layer. The retrieval device may bepositioned locally to the patch or may extend from the patch to aposition outside of the body while the device is implanted. In anexemplary embodiment, the retrieval device is a loop permanentlyattached to the patch with a string or extension that is configured,when the device is implanted, to extend to a position outside of thebody. The retrieval device is configured to transfer removal forces froma practitioner or snare to the patch and separate the patch from thestent and the grown growth layer. As shown, the retrieval device ispermanently attached on opposite sides of the terminal end of the patch.However, any configuration of retrieval device may be used. In the caseof a metal patch, the retrieval device may be welded to the patch. Inthe case of a wire mesh, the wires of the mesh may be extended tointegrally form the retrieval device.

In an exemplary embodiment, the retrieval device is configured to bepositioned in the center of the vessel when the patch is completelycovered by the growth layer. In an exemplary embodiment, the retrievaldevice is configured to extend from the implant location to a positionoutside of the body. For example, a wire may be used that is permanentlyattached to the patch and is sufficiently long to extend from anintended implant site in a vein to a position outside of the body. Theretrieval device may then act as a guidewire, permitting a retrievalsheath to be inserted thereover. When application of force is imposed onthe patch through the retrieval device, it may be used to position thepatch within a sheath positioned over the retrieval device, and bothremoved from the body.

FIG. 10 illustrates an exemplary flow diagram 1000 of a method of usingthe device described herein to form a valve within the vein throughminimally-invasive or less invasive procedures. As the foregoing textand figures may apparent, a method of creating the neovalve may includedelivering a device comprising a stent scaffold and a patch on a luminalsurface thereof to the target vein and leaving the device in placeaccording to known stenting or similar methods. After a sufficientperiod of time, such that the device is covered by vascular smoothmuscle cells, endothelial tissue, vascular tissue, and/or other cellularlayer, the patch may be separated from the stent scaffold and removedfrom the body. The removal of the patch creates a slit in the vesselwall between the vein wall and the growth layer formed over the patch.The space left behind the patch within the vessel wall may be used tocause the vessel wall layers to separate and permit the luminal side ofthe wall to act as a valve similar to the surgical neovalve.

At step 1002, a device according to embodiments described herein may bedelivered to a site within the body in which a valve is to be created.The device may define a reduced diameter delivery configurationpositioned on the end of a delivery device. The delivery device may be acatheter that may include an outer sheath and/or inner catheter having aregion to support the device and/or distal balloon. Navigating thedevice to a valve location and deploying the device at step 1004 may besimilar to conventional methods for positioning and deploying a stentwithin the vasculature. The device, the delivery device, andcombinations thereof may include visual markers or other system may beused to confirm the final location of the device before, during, and/orafter deployment. Once deployed, at step 1006, the device is left in thebody for a sufficient period of time to permit a layer of growth cellsto completely or substantially cover the patch and/or stent. Forexample, the device may be implanted in the body for approximately 4 to8 weeks. This step may also include preventing a portion of the patchfrom supporting cellular growth. For example, a drug to inhibit cellularor neointimal/endothelial proliferation may be coated or impregnatedinto or on a portion of the patch material, such that a portion of thepatch, such as a leading edge of the patch is not covered by a cellularlayer. At step 1008, once the growth layer is formed over the patch, thepatch is separated from the stent and at step 1010, the patch is removedfrom the body. The patch may be separated through degradation of theattachment between the patch and the stent, and/or through applicationof an external force, device, reaction, or initiator. In an exemplaryembodiment, a retrieval device is used to separate the patch and removeit from the body. The retrieval device may be permanently affixed to thepatch and either directly or indirectly used to apply an external forceor sheer force to the patch relative to the stent. In an exemplaryembodiment, the retrieval device is configured such that it remainsexposed in an interior of the vessel after the patch has been completelycovered with the growth layer. At step 2012, the removal of the patchcreates a gap between the growth layer and the stent and/or vessel wall.A valve is naturally formed by collapsing this separated tissue into thelumen of the vessel.

FIGS. 11A-11B illustrate an exemplary implantation of the deviceaccording to embodiments described herein after the patch has beenremoved. As shown, the device is positioned in a vessel 1102. After thepatch has been removed, the device consists of the stent structure 1104.The device has been overgrown with an growth layer 1106. With theremoval of the patch, a gap 1108 is left to form a flap or valve 1110.When the blood pressure moves the blood past the valve, as in FIG. 11A,the growth layer 1106 is pushed against the original or natural vesselwall 1102 and/or the stent 1104. When a back pressure is felt or acondition in which the blood would flow in an undesirable direction,illustrated in FIG. 11B, the flap or valve 1110 is pulled from thevessel wall 1102 and blocks the vessel lumen, thus preventing any backflow of blood. In an exemplary embodiment, the patch creates a slit atthe forward edge and a pocket between the growth layer and the vesselwall. In this case, when the valve is closed, a surface approximating aportion of a cone or dome blocks the vessel lumen.

Although embodiments of this invention have been fully described withreference to the accompanying drawings, it is to be noted that variouschanges and modifications will become apparent to those skilled in theart. Such changes and modifications are to be understood as beingincluded within the scope of embodiments of this invention as defined bythe appended claims. For example, exemplary embodiments are providedwith different combinations of features. However, any combination ofcomponents or features may be used and are within the scope of theinstant disclosure. For example, components may be integrated,subdivided, duplicated, removed, added, or otherwise recombined andremain within the scope of the instant invention. Similarly, withrespect to the exemplary methods, steps may be performed in variousorder, or steps may be recombined by duplicating, separating,integrating, removing or otherwise reconfiguring the steps and remainwithin the scope of the instant disclosure. It should also be understoodthat the term “comprising” is synonymous with “including” and does notmean “consisting only of”. Any use of the terms “and” or “or” isintended to include the other, such that any list of options, features,or components may include any combination of the identified optionsunless expressly limited.

Also, any patent, patent application, or other cited reference is herebyincorporated by reference in its entirety. Any such cited reference orgeneral description of the state of the art, background, or conventionalsystem or method is not an admission that any such disclosure is priorart or forms part of the common general knowledge.

1. A device, comprising: a support scaffold defining a lumen; and apatch removably attached to a luminal surface of the support scaffold.2. The device of claim 1, wherein the patch traverses only a portion ofa circumference of a luminal surface of the support scaffold such thatthe patch does not fully encircle the lumen of the support scaffold. 3.The device of claim 2, wherein the patch defines a leading terminal edgeand a trailing terminal edge and the leading terminal edge is configuredto inhibit cellular proliferation when implanted in a patient.
 4. Thedevice of claim 3, wherein the patch comprises a coating of a drug toinhibit cellular proliferation when implanted in the patient.
 5. Thedevice of claim 4, wherein the patch comprises a second coating of adrug to encourage cellular proliferation when implanted in the patient.6. The device of claim 3, wherein the support scaffold is a stent. 7.The device of claim 6, further comprising a retrieval device permanentlyattached to the patch.
 8. The device of claim 7, wherein the retrievaldevice is configured as a hook to be captured by a snare for removalfrom the patient.
 9. The device of claim 7, wherein the retrieval devicecomprising an extension that is configured to be positioned outside ofthe body when the patch is within the patient and attached to the patchto separate the patch from the stent and remove the patch from the bodyafter use.
 10. The device of claim 7, wherein the patch tapers from theleading terminal edge to a trailing terminal edge such that an arclength defined by a portion of the patch at the leading terminal edge islonger than an arc length defined by a portion of the patch at thetrailing terminal edge.
 11. A method of producing a neovalve in apatient using a percutaneous minimally invasive manner, comprising:implanting a device having a removable patch on a luminal surface of astent at a desired site for the neovalve within a vein; leaving thestent in place at the desired site for a sufficient period of time forgrowth tissue to cover at least a portion of the patch; removing thepatch from the patient thereby creating a slit in the vessel wallbetween the growth tissue and the vein; and separating the growth tissuefrom the vessel wall to act as a valve.
 12. The method of claim 11,further comprising providing the device wherein the patch traverses onlya portion of a circumference of the luminal surface of the stent suchthat the patch does not fully encircle a lumen of the stent.
 13. Themethod of claim 12, wherein the sufficient period of time is between 4and 8 weeks.
 14. The method of claim 12, wherein the removal of thepatch comprises engaging an exposed retrieval device permanentlyattached to the patch when the patch is at least partially covered bythe growth tissue.
 15. The method of claim 14, wherein the engaging isperformed with a snare within the vein.
 16. The method of claim 12,wherein the leaving of the stent in place further comprises positioninga retrieval device in a position at least partially outside of thepatient when the stent is in place at the desired site, and the removalof the patch comprises pulling on the retrieval device from outside ofthe patient.
 17. The method of claim 12, further comprising preventingthe proliferation of growth tissue along a leading terminal edge of thepatch.
 18. The device of claim 1, wherein the support scaffold is astent.